1. Field of the Invention
The present invention relates to a medical endoscope having an optical system enclosed by a system tube, the distal end of the optics duct being sealed by a window fitted at its inner surface with an electrical heating ring.
2. Description of Related Art
When employed as designed for, medical endoscopes are inserted by their distal end into a body-warm and moist body cavity while initially being still at the lower outside temperature. Inevitably the distal window fogs up. The surgeon must wait until the fog on the window disappears on account of temperature balancing and gradual evaporation and must resort to the conventional remedial steps, illustratively wiping dry the fogged-up window near a body part.
A number of window heating systems are known in the state of the art using diverse heating means, among which is electric power.
Illustratively, electrical heating systems are known from the U.S. Pat. No. 4,076,018 in which electrical conductors are applied to the inner window surface.
The US patent document 2007/0149856 A1 of this kind discloses, moreover, a temperature sensor to control the heating power, a heating ring being used and configured in the region between the distal system tube receiving a video system and the window.
The present state of the art addresses inadequately the problem of affixing the heating ring. The first aforementioned literature mentions several ways, illustratively the heating conductor being applied internally or externally to the window or being fused in it. Also this literature proposes configuring said conductor around the window.
Problems arise when the heating ring is mounted at the window. Illustratively adequate thermal contact might be attained by fusing, bonding and the like of the heater into/at the window, however at the cost of raising assembly problems. On the other hand, should the heating ring be merely deposited, the thermal contact would be inadequate.
Accordingly it is the objective of the present invention to optimize the heating ring configuration in an endoscope of the aforementioned kind.